JP7725446B2 - Anti-HER2/anti-4-1BB bispecific antibodies and uses thereof - Google Patents

Description

Anti-4-1BB/anti-HER2 bispecific antibodies and pharmaceutical compositions, as well as methods for using the same to treat and/or prevent cancer, are provided.

The 4-1BB protein is a member of the TNF receptor superfamily (TNFRSF) and a costimulatory molecule expressed after activation of both innate and adaptive immune cells. 4-1BB plays an important role in modulating the activity of various immune cells. 4-1BB agonists enhance immune cell proliferation and survival, cytokine secretion, and CD8 T cell cytolytic activity. Many other studies have shown that activation of 4-1BB enhances immune responses and eliminates tumors in mice. This suggests that 4-1BB is a promising target molecule in cancer immunology. Despite their antitumor effects, anti-4-1BB antibodies have induced severe liver toxicity in clinical applications.

The HER2 protein is a member of the epidermal growth factor receptor (EGFR) family and is involved in a variety of tumor-related mechanisms. HER2 is a typical receptor tyrosine kinase (RTK) that is present on the cell surface and thereby induces cancer cell proliferation and invasion, angiogenesis, and other processes.

Meanwhile, multispecific antibodies that target two or more antigens have been developed in a variety of types and forms, and are expected to become new drug antibodies with superior therapeutic effects compared to monoclonal antibodies.

Therefore, for more effective cancer treatment, it is necessary to develop multispecific antibodies that can recognize two different antigens, one present on cancer cells and the other present on other cells, such as immune cells.

Technical Problem One embodiment comprises:
Provided are anti-HER2/anti-4-1BB bispecific antibodies comprising: (1) an anti-HER2 antibody or antigen-binding fragment thereof as a HER2 targeting moiety, which is capable of specifically recognizing and/or specifically binding to HER2 protein; and (2) an anti-4-1BB antibody or antigen-binding fragment thereof as a 4-1BB targeting moiety, which is capable of specifically recognizing and/or specifically binding to 4-1BB protein.

Another embodiment provides a pharmaceutical composition comprising the bispecific antibody. The pharmaceutical composition may further comprise a pharmaceutically acceptable carrier. The pharmaceutical composition may be used to treat and/or prevent cancer and/or enhance an immune response.

Another embodiment provides a pharmaceutical composition for treating and/or preventing cancer and/or enhancing an immune response, the composition comprising a bispecific antibody.

Another embodiment provides a method for treating and/or preventing cancer in a subject in need thereof, comprising administering to the subject a pharmaceutically effective amount of a bispecific antibody or pharmaceutical composition. The method may further comprise the step of identifying the subject in need of cancer treatment and/or prevention prior to the administering step.

Another embodiment provides a method for enhancing an immune response in a subject in need thereof, comprising administering to the subject a pharmaceutically effective amount of a bispecific antibody or pharmaceutical composition. The method may further comprise the step of identifying the subject in need of an enhanced immune response prior to the administering step.

Another embodiment provides the use of a bispecific antibody or pharmaceutical composition in the treatment and/or prevention of cancer. Another embodiment provides the use of a bispecific antibody in the preparation of a medicament for treating and/or preventing cancer.

Another embodiment provides the use of a bispecific antibody or pharmaceutical composition in enhancing an immune response. Another embodiment provides the use of a bispecific antibody in the preparation of a medicament for enhancing an immune response.

One embodiment provides a polynucleotide encoding a bispecific antibody.

One embodiment provides a recombinant vector comprising the polynucleotide. The recombinant vector can be used as an expression vector for the polynucleotide encoding the bispecific antibody.

Another embodiment provides a cell containing a polynucleotide encoding the bispecific antibody. The cell may be a recombinant cell transfected with a recombinant vector containing the polynucleotide.

Another embodiment provides a method for preparing a bispecific antibody, the method comprising expressing a polynucleotide in a cell. The step of expressing the polynucleotide can be carried out by culturing a cell containing the polynucleotide (e.g., in a recombinant vector) under conditions that allow expression of the polynucleotide.

Technical Solution The present disclosure relates to bispecific antibodies, each of which comprises an antibody specific for a tumor-associated antigen (TAA; HER2) and an antibody specific for 4-1BB, and uses thereof. These bispecific antibodies activate 4-1BB signaling and potently boost immune cells only in the presence of HER2-expressing cells. Due to the specific HER2-mediated immune response, the use of bispecific antibodies is expected to significantly reduce liver toxicity compared to 4-1BB monoclonal antibodies.

The present disclosure provides an anti-HER2/anti-4-1BB bispecific antibody and uses thereof, wherein the anti-HER2/anti-4-1BB bispecific antibody is
(1) an anti-HER2 antibody or antigen-binding fragment thereof as the HER2 targeting moiety, which is capable of specifically recognizing and/or specifically binding to the HER2 protein; and (2) an anti-4-1BB antibody or antigen-binding fragment thereof as the 4-1BB targeting moiety, which is capable of specifically recognizing and/or specifically binding to the 4-1BB protein.

The present invention will be described in more detail further on in this specification.

Definitions As used herein, "consisting of a sequence,""consisting essentially of a sequence," or "comprising a sequence" may refer to any case in which the sequence is included, but may not be intended to exclude cases in which additional sequences other than the sequence are included.

As used herein, the terms "a protein or polypeptide comprising or consisting of an amino acid sequence identified by a SEQ ID NO" and "a gene or polynucleotide comprising or consisting of a nucleic acid sequence identified by a SEQ ID NO" may refer to a protein (or polypeptide) or gene (or polynucleotide) consisting essentially of an amino acid sequence or nucleic acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity with the amino acid sequence or nucleic acid sequence that maintains its inherent activity and/or function.

As used herein, the term "antibody" encompasses a wide variety of biochemically distinguishable polypeptide classes. Those skilled in the art will recognize that heavy chains are classified as gamma, mu, alpha, delta, or epsilon (γ, μ, α, δ, ε), with some subclasses between them (e.g., γ1-γ4), and light chains are classified as kappa (κ) or lambda (λ). It is the nature of this chain that determines the "class" of an antibody: IgG, IgM, IgA IgG, or IgE, respectively. Immunoglobulin subclasses (isotypes), e.g., IgG1, IgG2, IgG3, IgG4, IgG5, etc., are well characterized and are known to confer functional specialization.

An intact antibody contains two full-length light chains and two full-length heavy chains, each light chain linked to a heavy chain by a disulfide bond. Antibodies have heavy chain and light chain constant regions. The heavy chain constant region is of the gamma (γ), mu (μ), alpha (α), delta (δ), or epsilon (ε) type, which may be further categorized as gamma 1 (γ1), gamma 2 (γ2), gamma 3 (γ3), gamma 4 (γ4), alpha 1 (α1), or alpha 2 (α2). The light chain constant region is of the kappa (κ) or lambda (λ) type.

The term "heavy chain" refers to a full-length heavy chain or a fragment thereof comprising a variable region _VH containing sufficient amino acid sequence to confer specificity for an antigen, three constant regions C _H1 , C _H2 , and C _H3 , and a hinge. The term "light chain" refers to a full-length light chain or a fragment thereof comprising a variable region _VL containing sufficient amino acid sequence to confer specificity for an antigen, and a constant region C _L.

The term "complementarity-determining region (CDR)" refers to an amino acid sequence found within the hypervariable region of an immunoglobulin heavy or light chain. The heavy and light chains may each contain three CDRs (CDRH1, CDRH2, and CDRH3; and CDRL1, CDRL2, and CDRL3). CDRs may provide residues that play important roles in antibody binding to an antigen or epitope. Those skilled in the art are familiar with the terms "specifically binding to" or "specifically recognized," which refer to an antibody and antigen that interact specifically with each other to result in immunological activity.

In the present disclosure, antibodies may include, but are not limited to, polyclonal or monoclonal antibodies; and/or human antibodies, humanized antibodies, animal-derived antibodies (e.g., mouse, rabbit, etc.), or chimeric antibodies (e.g., mouse-human chimeric antibodies).

Animal-derived antibodies produced by immunizing animals with a desired antigen can generally induce immune rejection when administered to humans for therapeutic purposes. Chimeric antibodies have been developed to suppress such immune rejection. Chimeric antibodies are formed by using genetic engineering techniques to replace the constant region of an animal-derived antibody, which is responsible for anti-isotype reactions, with the constant region of a human antibody. While chimeric antibodies have significantly improved anti-isotype reactions compared to animal-derived antibodies, they still contain animal-derived amino acids in their variable regions, and therefore still contain potential side effects resulting from anti-idiotype reactions. Thus, humanized antibodies have been developed to address such side effects. Humanized antibodies are produced by grafting the CDRs (complementarity-determining regions), which play an important role in antigen binding, from the variable regions of a chimeric antibody onto a human antibody framework.

As used herein, the term "antigen-binding fragment" refers to a fragment derived from an intact immunoglobulin structure that includes a portion capable of binding to an antigen, such as a CDR. For example, an antigen-binding fragment can be, but is not limited to, an scFv, (scFv) ₂ , Fab, Fab', or F(ab') ₂ . In the present disclosure, an antigen-binding fragment can be, for example, a fragment derived from an antibody that includes at least one complementarity-determining region selected from the group consisting of scFv, (scFv) 2 , scFv-Fc, Fab, Fab', and F(ab') 2 .

Among the antigen-binding fragments, Fab has a structure comprising light-chain and heavy-chain variable regions, a light-chain constant region, and the first heavy-chain constant region (C _H1 ), and has one antigen-binding site.

Fab' differs from Fab in that it has a hinge region containing one or more cysteine residues at the C-terminus of the heavy chain _CH1 domain, and F(ab') ₂ antibodies are formed through disulfide bond formation of the cysteine residues in the hinge region of Fab'.

An Fv is a minimal antibody fragment containing only the heavy-chain variable region and the light-chain variable region, and recombinant methods for producing Fv fragments are well known in the relevant art. A two-chain Fv may have a structure in which the heavy-chain variable region is non-covalently linked to the light-chain variable region, while a single-chain Fv (scFv) may generally have a dimeric structure, as in a two-chain Fv, in which the heavy-chain variable region and the light-chain variable region are covalently linked via a peptide linker or directly linked to each other at their C-termini.

Antigen-binding fragments may be obtained using proteases (for example, whole antibodies may be digested with papain to obtain Fab fragments or with pepsin to obtain F(ab') ₂ fragments) or may be prepared by recombinant methods.

The immunoglobulin (e.g., human immunoglobulin) or antibody molecules of the present disclosure can be of any type (e.g., IgG, IgE, IgM, IgD, IgA, IgY, etc.), class (e.g., IgG1, IgG2, IgG3, IgG4, IgG5, IgA1, IgA2, etc.), or subclass of immunoglobulin molecule.

Within an antibody or antibody fragment, portions excluding the CDRs or variable regions (e.g., constant regions) may be derived from a human antibody, and in particular, portions excluding the CDRs or variable regions may be derived from IgG, IgA, IgD, IgE, IgM, or IgY, e.g., IgG1, IgG2, IgG3, or IgG4.

Antibodies or antigen-binding fragments may be chemically or recombinantly synthesized (non-naturally occurring).

4-1BB Targeting Moiety Anti-HER2/anti-4-1BB bispecific antibodies may comprise an anti-4-1BB antibody or an antigen-binding fragment thereof as a 4-1BB targeting moiety.

The term "4-1BB," also referred to as CD137 or TNFRSF9 (TNF receptor superfamily member 9), is a member of the TNF receptor superfamily (TNFRSF) and is a costimulatory molecule expressed following activation of immune cells, both innate and adaptive. 4-1BB plays an important role in modulating the activity of various immune cells. As used herein, 4-1BB may be derived from a mammal, for example, a human (Homo sapiens) (NCBI accession number: NP_001552.2). For example, the human 4-1BB protein (NP_001552.2) has the following amino acid sequence (SEQ ID NO: 89):
1 mgnscyniva tlllvlnfer trslqdpcsn cpagtfcdnn rnqicspcpp nsfssaggqr
61 tcdicrqckg vfrtrkecss tsnaecdctp gfhclgagcs mceqdckqgq eltkkgckdc
121 cfgtfndqkr gicrpwtncs ldgksvlvng tkerdvvcgp spadlspgas svtppapare
181 pghspqiisf flatstall flffltlrf svvkrgrkkl lyifkqpfmr pvqttqeedg
241 cscrfpeeeee ggcel
It can be expressed as follows:

In some embodiments, the anti-4-1BB antibody or antigen-binding fragment thereof is
CDR (complementarity determining region)-H1 (H-CDR1) comprising the amino acid sequence of SEQ ID NO: 1, 2, or 3;
an H-CDR2 comprising the amino acid sequence of SEQ ID NO: 4, 5, or 6;
an H-CDR3 comprising the amino acid sequence of SEQ ID NO: 7, 8, 9, 10, or 11;
L-CDR1 comprising the amino acid sequence of SEQ ID NO: 12 or 13;
L-CDR2 comprising the amino acid sequence of SEQ ID NO: 14 or 15; and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 16 or 17.
may include:

The amino acid sequences of the CDRs of anti-4-1BB antibodies or antigen-binding fragments are illustrated in Table 1.

For example, the anti-4-1BB antibody or antigen-binding fragment thereof may be
H-CDR1 comprising the amino acid sequence of SEQ ID NO: 1, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 4, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 7, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 12, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 14, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 16;
H-CDR1 comprising the amino acid sequence of SEQ ID NO: 1, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 4, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 8, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 12, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 14, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 16;
H-CDR1 comprising the amino acid sequence of SEQ ID NO: 1, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 4, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 9, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 12, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 14, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 16;
H-CDR1 comprising the amino acid sequence of SEQ ID NO: 1, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 4, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 7, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 13, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 15, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 17;
H-CDR1 comprising the amino acid sequence of SEQ ID NO: 1, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 4, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 8, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 13, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 15, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 17;
H-CDR1 comprising the amino acid sequence of SEQ ID NO: 1, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 4, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 9, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 13, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 15, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 17;
H-CDR1 comprising the amino acid sequence of SEQ ID NO: 2, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 5, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 10, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 12, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 14, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 16;
H-CDR1 comprising the amino acid sequence of SEQ ID NO: 2, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 5, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 10, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 13, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 15, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 17;
H-CDR1 comprising the amino acid sequence of SEQ ID NO:3, H-CDR2 comprising the amino acid sequence of SEQ ID NO:6, H-CDR3 comprising the amino acid sequence of SEQ ID NO:11, L-CDR1 comprising the amino acid sequence of SEQ ID NO:12, L-CDR2 comprising the amino acid sequence of SEQ ID NO:14, and L-CDR3 comprising the amino acid sequence of SEQ ID NO:16; or H-CDR1 comprising the amino acid sequence of SEQ ID NO:3, H-CDR2 comprising the amino acid sequence of SEQ ID NO:6, H-CDR3 comprising the amino acid sequence of SEQ ID NO:11, L-CDR1 comprising the amino acid sequence of SEQ ID NO:13, L-CDR2 comprising the amino acid sequence of SEQ ID NO:15, and L-CDR3 comprising the amino acid sequence of SEQ ID NO:17
may include:

In another embodiment, the anti-4-1BB antibody or antigen-binding fragment thereof may comprise a heavy chain variable region comprising an H-CDR1 comprising the amino acid sequence of SEQ ID NO: 1, 2, or 3, an H-CDR2 comprising the amino acid sequence of SEQ ID NO: 4, 5, or 6, and an H-CDR3 comprising the amino acid sequence of SEQ ID NO: 7, 8, 9, 10, or 11; and a light chain variable region comprising an L-CDR1 comprising the amino acid sequence of SEQ ID NO: 12 or 13, an L-CDR2 comprising the amino acid sequence of SEQ ID NO: 14 or 15, and an L-CDR3 comprising the amino acid sequence of SEQ ID NO: 16 or 17.

In another embodiment, the anti-4-1BB antibody or antigen-binding fragment thereof may comprise a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, or 29; and a light chain variable region comprising or consisting essentially of the amino acid sequence of SEQ ID NO: 30, 31, 32, 33, 34, or 88.

The amino acid sequences of the variable regions of anti-4-1BB antibodies or antigen-binding fragments are exemplified in Table 2.

For example, the anti-4-1BB antibody or antigen-binding fragment thereof may be
a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, or 29, and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 30;
a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, or 29, and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 31;
a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, or 29, and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 32;
a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, or 29, and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 33;
a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, or 29, and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 34; or a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, or 29, and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 88.

The framework amino acid sequences of the variable regions of anti-4-1BB antibodies or antigen-binding fragments are exemplified in Table 3.

In another embodiment, the anti-4-1BB antibody or antigen-binding fragment thereof may comprise a heavy chain comprising or consisting essentially of the amino acid sequence of SEQ ID NO: 56, 57, 58, 59, 60, or 61; and a light chain comprising or consisting essentially of the amino acid sequence of SEQ ID NO: 62, 63, or 64.

For example, the anti-4-1BB antibody or antigen-binding fragment thereof may be
a heavy chain comprising, or consisting essentially of, the amino acid sequence of SEQ ID NO: 56, 57, 58, 59, 60, or 61; and a light chain comprising, or consisting essentially of, the amino acid sequence of SEQ ID NO: 62;
a heavy chain comprising, or consisting essentially of, the amino acid sequence of SEQ ID NO: 56, 57, 58, 59, 60, or 61; and a light chain comprising, or consisting essentially of, the amino acid sequence of SEQ ID NO: 63; or a heavy chain comprising, or consisting essentially of the amino acid sequence of SEQ ID NO: 56, 57, 58, 59, 60, or 61; and a light chain comprising, or consisting essentially of the amino acid sequence of SEQ ID NO: 64.

In another embodiment, the anti-4-1BB antibody or antigen-binding fragment thereof is
a heavy chain variable region comprising an H-CDR1 comprising the amino acid sequence of SEQ ID NO: 1, 2, or 3, an H-CDR2 comprising the amino acid sequence of SEQ ID NO: 4, 5, or 6, and an H-CDR3 comprising the amino acid sequence of SEQ ID NO: 7, 8, 9, 10, or 11; and a light chain variable region comprising an L-CDR1 comprising the amino acid sequence of SEQ ID NO: 12 or 13, an L-CDR2 comprising the amino acid sequence of SEQ ID NO: 14 or 15, and an L-CDR3 comprising the amino acid sequence of SEQ ID NO: 16 or 17,
The heavy chain variable region and the light chain variable region can be linked to each other in any order, either directly (i.e., without a linker) or via a peptide linker.
It may be an scFv (single chain variable fragment).

For example, the anti-4-1BB scFv is
a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, or 29; and a light chain variable region comprising or consisting essentially of the amino acid sequence of SEQ ID NO: 30, 31, 32, 33, 34, or 88,
In this case, the heavy chain variable region and the light chain variable region can be linked to each other in any order, either directly or via a peptide linker.

For example, the anti-4-1BB scFv is
a heavy chain variable region comprising, or consisting essentially of, the amino acid sequence of SEQ ID NO: 24, 25, 26, 27, 28, or 29; and a light chain variable region comprising, or consisting essentially of, SEQ ID NO: 33;
a heavy chain variable region comprising, or consisting essentially of, the amino acid sequence of SEQ ID NO: 24, 25, 26, 27, 28, or 29; and a light chain variable region comprising, or consisting essentially of, SEQ ID NO: 34; or a heavy chain variable region comprising, the amino acid sequence of SEQ ID NO: 24, 25, 26, 27, 28, or 29, and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 88,
In this case, the heavy chain variable region and the light chain variable region can be linked to each other in any order, either directly or via a peptide linker.

In the present disclosure, an anti-4-1BB scFv comprises a heavy chain variable region and a light chain variable region in any order. For example, an anti-4-1BB scFv may comprise a light chain variable region and a heavy chain variable region in the N-terminal to C-terminal direction. Alternatively, an anti-4-1BB scFv may comprise a heavy chain variable region and a light chain variable region in the N-terminal to C-terminal direction.

HER2 Targeting Moiety The anti-HER2/anti-4-1BB bispecific antibody may comprise an anti-HER2 antibody, or an antigen-binding fragment thereof, as the HER2 targeting moiety.

"HER2 (human epidermal growth factor receptor 2)" is encoded by the ERBB2 gene and is a member of the epidermal growth factor receptor (EGFR/ErbB) family. HER2 is known to play an essential role in regulating cell proliferation and differentiation. In particular, when bound to extracellular growth factors, HER2 exhibits a strong tendency to assemble into homodimers and/or heterodimers with other HER receptors, resulting in the activation of several forms of signal transduction pathways and inducing apoptosis, survival, or cell proliferation. For example, the HER2 protein may be a polypeptide deposited under GenBank accession numbers NP_004439.2, NP_001005862.1, etc., encoded by a nucleotide sequence (mRNA) deposited under GenBank accession numbers NM_004448.4, NM_001005862.3, etc., respectively.

In one embodiment, the anti-HER2 antibody may be selected from the group consisting of trastuzumab, pertuzumab, and trastuzumab emtansine (T-DM1).

The antigen-binding region of an anti-HER2 antibody that recognizes HER2 as an antigen may be scFv, (scFv) ₂ , Fab, Fab', or F(ab') ₂ of an anti-HER2 antibody selected from the group consisting of trastuzumab, pertuzumab, and trastuzumab emtansine (T-DM1).

The anti-HER2 antibody or antigen-binding fragment thereof may be an anti-HER2 antibody or antigen-binding fragment thereof comprising the six CDRs of trastuzumab, pertuzumab, or trastuzumab emtansine (T-DM1).

In some embodiments, the anti-HER2 antibody or antigen-binding fragment thereof may be trastuzumab or an antigen-binding fragment thereof, or a variant thereof.

For example, the anti-HER2 antibody or antigen-binding fragment thereof may be
H-CDR1 comprising the amino acid sequence of SEQ ID NO: 65;
H-CDR2 comprising the amino acid sequence of SEQ ID NO: 66;
H-CDR3 comprising the amino acid sequence of SEQ ID NO: 67;
L-CDR1 comprising the amino acid sequence of SEQ ID NO: 68;
L-CDR2 comprising the amino acid sequence of SEQ ID NO: 69; and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 70.
may include:

The amino acid sequences of the CDRs of anti-HER2 antibodies or antigen-binding fragments are illustrated in Table 4.

In another embodiment, the anti-HER2 antibody or antigen-binding fragment thereof may comprise a heavy chain variable region comprising an H-CDR1 comprising the amino acid sequence of SEQ ID NO: 65, an H-CDR2 comprising the amino acid sequence of SEQ ID NO: 66, and an H-CDR3 comprising the amino acid sequence of SEQ ID NO: 67; and a light chain variable region comprising an L-CDR1 comprising the amino acid sequence of SEQ ID NO: 68, an L-CDR2 comprising the amino acid sequence of SEQ ID NO: 69, and an L-CDR3 comprising the amino acid sequence of SEQ ID NO: 70.

In another embodiment, the anti-HER2 antibody or antigen-binding fragment thereof may comprise a heavy chain variable region comprising or consisting essentially of the amino acid sequence of SEQ ID NO: 71, and a light chain variable region comprising or consisting essentially of the amino acid sequence of SEQ ID NO: 72.

The amino acid sequences of the variable regions of anti-HER2 antibodies or antigen-binding fragments are exemplified in Table 5.

In another embodiment, the anti-HER2 antibody or antigen-binding fragment thereof may comprise a heavy chain comprising, or consisting essentially of, the amino acid sequence of SEQ ID NO: 73 or 74; and a light chain comprising, or consisting essentially of, the amino acid sequence of SEQ ID NO: 75.

In another embodiment, the anti-HER2 antibody or antigen-binding fragment thereof is
a heavy chain variable region comprising an H-CDR1 comprising the amino acid sequence of SEQ ID NO: 65, an H-CDR2 comprising the amino acid sequence of SEQ ID NO: 66, and an H-CDR3 comprising the amino acid sequence of SEQ ID NO: 67; and a light chain variable region comprising an L-CDR1 comprising the amino acid sequence of SEQ ID NO: 68, an L-CDR2 comprising the amino acid sequence of SEQ ID NO: 69, and an L-CDR3 comprising the amino acid sequence of SEQ ID NO: 70,
The heavy chain variable region and the light chain variable region can be linked to each other in any order, either directly (i.e., without a linker) or via a peptide linker.
It may be an scFv (single chain variable fragment).

In another embodiment, the anti-HER2 antibody or antigen-binding fragment thereof is
a heavy chain variable region comprising, or consisting essentially of, the amino acid sequence of SEQ ID NO: 71; and a light chain variable region comprising, or consisting essentially of, the amino acid sequence of SEQ ID NO: 72,
The heavy chain variable region and the light chain variable region can be linked to each other in any order, either directly or via a peptide linker.
It may be an scFv (single chain variable fragment).

In the present disclosure, an anti-HER2 scFv comprises a heavy chain variable region and a light chain variable region in any order. For example, an anti-HER2 scFv may comprise a light chain variable region and a heavy chain variable region in an N-terminal to C-terminal direction. Alternatively, an anti-HER2 scFv may comprise a heavy chain variable region and a light chain variable region in an N-terminal to C-terminal direction.

Bispecific antibodies The present disclosure provides
The present invention provides an anti-HER2/anti-4-1BB bispecific antibody comprising: (1) an anti-HER2 antibody or antigen-binding fragment thereof as the HER2 targeting moiety, which is capable of specifically recognizing and/or specifically binding to the HER2 protein; and (2) an anti-4-1BB antibody or antigen-binding fragment thereof as the 4-1BB targeting moiety, which is capable of specifically recognizing and/or specifically binding to the 4-1BB protein.

Anti-HER2/anti-4-1BB bispecific antibodies can activate 4-1BB signaling only when crosslinked by HER2-expressing tumor cells. In addition, the anti-4-1BB antibody or antigen-binding fragment thereof contained within the bispecific antibody can be characterized by localizing and/or being activated only within the tumor microenvironment (TME) and/or exhibiting significantly reduced liver toxicity compared to existing anti-4-1BB antibodies, while maintaining immune response enhancement and/or tumor treatment efficacy.

In one embodiment, a bispecific antibody can comprise a full-length anti-HER2 antibody and an antigen-binding fragment (e.g., scFv) of an anti-4-1BB antibody, in which case the antigen-binding fragment of the anti-4-1BB antibody can be linked to the N-terminus, C-terminus, or both of the full-length anti-HER2 antibody, either directly or via a peptide linker. In another embodiment, a bispecific antibody can comprise a full-length anti-4-1BB antibody and an antigen-binding fragment (e.g., scFv) of an anti-HER2 antibody, in which case the antigen-binding fragment of the anti-HER2 antibody can be linked to the N-terminus, C-terminus, or both of the full-length anti-4-1BB antibody, either directly or via a peptide linker.

In certain embodiments, the scFv contained in the bispecific antibody may comprise a heavy chain variable region and a light chain variable region in any order. For example, the scFv contained in the bispecific antibody may comprise a light chain variable region and a heavy chain variable region in an N-terminal to C-terminal direction, optionally with a peptide linker between them; alternatively, the scFv contained in the bispecific antibody may comprise a heavy chain variable region and a light chain variable region in an N-terminal to C-terminal direction, optionally with a peptide linker between them.

When the bispecific antibody comprises a full-length anti-HER2 antibody and an anti-4-1BB scFv, the bispecific antibody comprises:
(i) in the N-terminal to C-terminal direction,
the heavy chain of an anti-HER2 antibody;
optionally, a peptide linker (first peptide linker), and an anti-4-1BB scFv
(ii) a first polypeptide comprising the light chain of an anti-HER2 antibody; and
In this case, the anti-4-1BB scFv is arranged in the N-terminal to C-terminal direction as follows:
The light chain variable region of an anti-4-1BB antibody,
Optionally, it may include a peptide linker (second peptide linker), and the heavy chain variable region of an anti-4-1BB antibody.

Alternatively, the bispecific antibody may comprise:
(i) in the N-terminal to C-terminal direction,
anti-4-1BB scFv,
Optionally, the antibody may comprise a peptide linker (first peptide linker), and a first polypeptide comprising the heavy chain of an anti-HER2 antibody; and (ii) a second polypeptide comprising the light chain of an anti-HER2 antibody,
The anti-4-1BB scFv is composed of the following in the N- to C-terminal direction:
The light chain variable region of an anti-4-1BB antibody,
Optionally, it may include a peptide linker (second peptide linker), and the heavy chain variable region of an anti-4-1BB antibody.

Alternatively, the bispecific antibody may comprise:
(i) in the N-terminal to C-terminal direction,
the heavy chain of an anti-HER2 antibody;
optionally, a peptide linker (first peptide linker), and an anti-4-1BB scFv
(ii) a first polypeptide comprising the light chain of an anti-HER2 antibody; and
The anti-4-1BB scFv is composed of the following in the N- to C-terminal direction:
The heavy chain variable region of an anti-4-1BB antibody,
Optionally, it may include a peptide linker (second peptide linker), and the light chain variable region of an anti-4-1BB antibody.

Alternatively, the bispecific antibody may comprise:
(i) in the N-terminal to C-terminal direction,
anti-4-1BB scFv,
Optionally, the antibody may comprise a peptide linker (first peptide linker), and a first polypeptide comprising the heavy chain of an anti-HER2 antibody; and (ii) a second polypeptide comprising the light chain of an anti-HER2 antibody,
The anti-4-1BB scFv is composed of the following in the N- to C-terminal direction:
The heavy chain variable region of an anti-4-1BB antibody,
Optionally, it may include a peptide linker (second peptide linker), and the light chain variable region of an anti-4-1BB antibody.

When the bispecific antibody comprises a full-length anti-4-1BB antibody and an anti-HER2 scFv, the bispecific antibody comprises:
(i) in the N-terminal to C-terminal direction,
the heavy chain of an anti-4-1BB antibody,
optionally, a peptide linker (first peptide linker), and an anti-HER2 scFv
(ii) a first polypeptide comprising the light chain of an anti-4-1BB antibody; and
In this case, the anti-HER2 scFv is arranged in the N-terminal to C-terminal direction as follows:
a light chain variable region of an anti-HER2 antibody;
Optionally, it may include a peptide linker (second peptide linker), and a heavy chain variable region of an anti-HER2 antibody.

Alternatively, the bispecific antibody may comprise:
(i) in the N-terminal to C-terminal direction,
anti-HER2 scFv,
Optionally, the antibody may comprise a peptide linker (first peptide linker), and (ii) a first polypeptide comprising the heavy chain of an anti-4-1BB antibody; and (ii) a second polypeptide comprising the light chain of an anti-4-1BB antibody,
In this case, the anti-HER2 scFv is arranged in the N-terminal to C-terminal direction as follows:
a light chain variable region of an anti-HER2 antibody;
Optionally, it may include a peptide linker (second peptide linker), and a heavy chain variable region of an anti-HER2 antibody.

Alternatively, the bispecific antibody may comprise:
(i) in the N-terminal to C-terminal direction,
the heavy chain of an anti-4-1BB antibody,
optionally, a peptide linker (first peptide linker), and an anti-HER2 scFv
(ii) a second polypeptide comprising the light chain of an anti-4-1BB antibody, wherein the anti-HER2 scFv comprises, in the N-terminal to C-terminal direction:
a heavy chain variable region of an anti-HER2 antibody;
Optionally, it may include a peptide linker (second peptide linker), and a light chain variable region of an anti-HER2 antibody.

Alternatively, the bispecific antibody may comprise:
(i) in the N-terminal to C-terminal direction,
anti-HER2 scFv,
Optionally, the anti-HER2 scFv may comprise a peptide linker (first peptide linker), and (ii) a first polypeptide comprising the heavy chain of an anti-4-1BB antibody; and (ii) a second polypeptide comprising the light chain of an anti-4-1BB antibody, wherein the anti-HER2 scFv comprises, in the N-terminal to C-terminal direction:
a heavy chain variable region of an anti-HER2 antibody;
Optionally, it may include a peptide linker (second peptide linker), and a light chain variable region of an anti-HER2 antibody.

The first peptide linker and the second peptide linker may or may not be present, and may be the same as or different from each other, independently within the bispecific antibody.

In another embodiment, both the HER2 targeting moiety and the 4-1BB targeting moiety contained within the bispecific antibody may be full-length antibodies or antigen-binding fragments comprising heavy chain CDRs, light chain CDRs, or a combination thereof, linked to each other directly or via a peptide linker.

Given that each of the antibodies can bind to both 4-1BB (such as human 4-1BB) and HER2 (such as human HER2), the CDR sequences, or V _H (heavy chain variable region) and V _L (light chain variable region) sequences disclosed herein can be "mixed and matched" to create other anti-HER2/anti-4-1BB binding bispecific molecules.

Peptide Linker For high antibody purity, the bispecific antibody may comprise a peptide linker between the heavy chain and the scFv in the first polypeptide (first peptide linker), and/or a peptide linker between the heavy chain variable region and the light chain variable region in the scFv (second peptide linker).

As used herein, the term "peptide linker" may refer to an oligopeptide comprising 1 to 100 amino acids, particularly 2 to 50 amino acids, each of which may be any type of amino acid without any limitations. Any conventional peptide linker may be used with or without appropriate modifications suited to a specific purpose. In specific embodiments, the peptide linker may contain, for example, Gly, Asn, and/or Ser residues, and/or may contain neutral amino acids such as Thr and/or Ala. Amino acid sequences suitable for peptide linkers may be known in the relevant technical field. The length of the peptide linker may be appropriately determined within such limits so that the function of the polypeptide and/or scFv is not affected. For example, a peptide linker can be formed by including a total of about 1 to about 100 amino acids, about 2 to about 50 amino acids, or about 5 to about 25 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, ₂₄ , or 25) amino acids, each of which is independently selected from the group consisting of Gly, Asn, Ser, Thr, and Ala. In one embodiment, the peptide linker can be represented as ( _GmSl ) _n , where m, l, and n are the number of "G", " _S ", and "( _GmSl )", respectively, and are independently selected from the integers of about 1 to about 10, particularly 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. In one embodiment, the peptide linker can be, but is not limited to, (GGGGS)2, (GGGGS)3, (GGGGS)4, or (GS)9 amino acids.

Medical Uses Medical uses of bispecific antibodies are provided for enhancing immune responses and/or treating and/or preventing cancer.

More specifically, embodiments provide pharmaceutical compositions comprising a bispecific antibody as an active ingredient. The pharmaceutical composition may further comprise a pharmaceutically acceptable carrier. The pharmaceutical composition may be used to enhance immune responses and/or treat and/or prevent cancer.

Another embodiment provides a pharmaceutical composition for treating and/or preventing cancer, the composition comprising a bispecific antibody as an active ingredient.

Another embodiment provides a method for treating and/or preventing cancer in a subject in need thereof, comprising administering to the subject a pharmaceutically effective amount of a bispecific antibody or pharmaceutical composition. The method may further comprise the step of identifying the subject in need of cancer treatment and/or prevention prior to the administering step.

Another embodiment provides the use of a bispecific antibody or pharmaceutical composition in the treatment and/or prevention of cancer. Another embodiment provides the use of a bispecific antibody in the preparation of a medicament for treating and/or preventing cancer.

In some embodiments, the cancer may be characterized by HER2 expression or overexpression of HER2 (compared to normal).

Another embodiment provides a pharmaceutical composition for enhancing an immune response, the composition comprising a bispecific antibody as an active ingredient.

Another embodiment provides a method for enhancing an immune response in a subject in need thereof, comprising administering to the subject a pharmaceutically effective amount of a bispecific antibody or pharmaceutical composition. The method may further comprise the step of identifying the subject in need of an enhanced immune response prior to the administering step.

Another embodiment provides the use of a bispecific antibody or pharmaceutical composition in enhancing an immune response. Another embodiment provides the use of a bispecific antibody in the preparation of a medicament for enhancing an immune response.

In some embodiments, the bispecific antibody or pharmaceutical composition may enhance an immune response, provided that HER2 is present. For example, in a method of enhancing an immune response, a subject may have HER2-expressing or HER2-overexpressing cells (e.g., HER2-expressing or HER2-overexpressing cancer cells).

The cancers prevented and/or treated by the bispecific antibodies or pharmaceutical compositions may be associated with 4-1BB and/or HER2, particularly HER2-expressing or HER2-overexpressing cancers. The cancer may be selected from solid cancers and hematological cancers. The cancer may be one or more cancers selected from the group consisting of, but not limited to, breast cancer, colon cancer, gastric cancer, lung cancer (e.g., lung squamous cell carcinoma, small cell lung cancer, non-small cell lung cancer, lung adenocarcinoma), peritoneal cancer, skin cancer, squamous cell carcinoma, melanoma of the skin or eye, rectal cancer, perianal cancer, esophageal cancer, small intestine tumor, endocrine gland cancer, parathyroid cancer, adrenal cancer, soft tissue sarcoma, urethral cancer, chronic or acute leukemia, lymphocytic lymphoma, liver cancer, gastrointestinal cancer, pancreatic cancer, glioblastoma, cervical cancer, ovarian cancer, liver cancer, bladder cancer, hepatocellular adenoma, colorectal cancer, endometrial or uterine cancer, salivary gland tumor, kidney cancer, cervical cancer, prostate cancer, vulvar cancer, thyroid cancer, head and neck cancer, brain cancer, bile duct cancer, gallbladder cancer, etc. The cancer may be a primary cancer or a metastatic cancer.

As used herein, the term "prevention and/or treatment of cancer" may refer to cancer cell death, inhibition of cancer cell proliferation, alleviation of symptoms associated with cancer, inhibition of cancer metastasis, etc.

As used herein, the term "enhanced immune response" may refer to the enhancement of any immune response associated with 4-1BB, such as activation of 4-1BB signaling or activation of 4-1BB-induced signals (e.g., but not limited to, activation of 4-1BB-induced NF-kB signaling, increased cytokine release, killing of target cells by immune cells such as T cells, etc.). In some embodiments, the enhancement of immune responses by the bispecific antibodies provided by the present disclosure may occur in the presence of HER2.

In addition to the bispecific antibody as an active ingredient, the pharmaceutical composition may further comprise a pharmaceutically acceptable carrier, diluent, and/or additive. The pharmaceutically acceptable carrier, diluent, and/or additive may be any pharmaceutically acceptable carrier, diluent, and/or additive selected from those commonly used for formulating antibodies. For example, the pharmaceutically acceptable carrier may be one or more pharmaceutically acceptable carriers selected from the group consisting of lactose, dextrose, sucrose, sorbitol, mannitol, starch, acacia gum, calcium phosphate, alginate, gelatin, calcium silicate, microcrystalline cellulose, polyvinylpyrrolidone, cellulose, water, syrup, methylcellulose, methyl hydroxybenzoate, propyl hydroxybenzoate, talc, magnesium stearate, and mineral oil, but is not limited to these.

The pharmaceutical composition may further comprise one or more agents selected from the group consisting of lubricants, wetting agents, sweeteners, flavor enhancers, emulsifiers, suspending agents, preservatives, etc.

A bispecific antibody or pharmaceutical composition may be administered to a subject orally or parenterally. Parenteral administration may be intravenous, subcutaneous, intramuscular, intraperitoneal, intradermal, topical, intranasal, intrapulmonary, or rectal administration. Because oral administration results in digestion of proteins or peptides, active ingredients in compositions for oral administration must be coated or formulated to prevent digestion in the stomach. In addition, the composition may be administered using any device that allows the active ingredient to be delivered to target cells (e.g., cancer cells).

As used herein, the term "pharmaceutically effective amount" may refer to an amount of a bispecific antibody, which is an active ingredient, capable of exerting a pharmaceutically meaningful effect in the prevention or treatment of cancer. The pharmaceutically effective amount of a bispecific antibody, or the appropriate dosage of a pharmaceutical composition, indicated by the amount of the bispecific antibody, may be formulated in various ways depending on a variety of factors, such as the patient's age, body weight, sex, condition, diet, excretion rate, and/or reaction sensitivity, type of formulation, number of doses, route of administration, and mode of administration. For example, the pharmaceutically effective amount of a bispecific antibody, or the appropriate dosage of a pharmaceutical composition, may be in the range of about 0.001 to about 1000 mg (amount of bispecific antibody) per kg (body weight) per day for an adult, about 0.01 to about 100 mg/kg, or 0.1 to 50 mg/kg.

The subject to which the bispecific antibody or pharmaceutical composition is administered may be, but is not limited to, a subject selected from mammals, such as humans, monkeys, rats, mice, dogs, cats, guinea pigs, rabbits, rats, mice, horses, cattle, cows, etc., or cells or tissues obtained therefrom, and may be a subject suffering from cancer.

The pharmaceutical composition can be formulated into a unit dosage form or a multi-dosage form with pharmaceutically acceptable carriers and/or additives by methods readily practiced by those skilled in the art. The dosage form can be a solution in an oily or aqueous medium, a suspension, a syrup, an emulsion, an extract, a powder, granules, a tablet, or a capsule, and can further include a dispersing agent or stabilizer.

Polynucleotides, Recombinant Vectors, and Antibody Preparations Certain embodiments provide polynucleotides encoding bispecific antibodies. For example, the polypeptide may comprise a first polynucleotide encoding the heavy chain of an anti-Her2 antibody described herein and the scFv of an anti-4-1BB antibody described herein, linked directly or via a peptide linker, and a second polynucleotide encoding the light chain of the anti-HER2 antibody. Alternatively, the polypeptide may comprise a first polynucleotide encoding the heavy chain of an anti-4-1BB antibody described herein and the scFv of an anti-HER2 antibody described herein, linked directly or via a peptide linker, and a second polynucleotide encoding the light chain of the anti-4-1BB antibody.

Another embodiment provides a recombinant vector comprising the polynucleotide. For example, the recombinant vector may comprise a first polynucleotide and a second polynucleotide together in one vector, or separately in two vectors. Another embodiment provides a recombinant cell comprising the first polynucleotide and the second polynucleotide. For example, the recombinant cell may be a cell transfected with the recombinant vector.

Another embodiment provides a method for preparing a bispecific antibody, the method comprising expressing polynucleotides, e.g., a first polynucleotide and a second polynucleotide, in a cell. The step of expressing the polynucleotides may be carried out by culturing cells containing the polynucleotides (e.g., in a recombinant vector) under conditions that allow expression of the polynucleotides. The method may further comprise isolating and/or purifying the anti-4-1BB antibody or antigen-binding fragment thereof from the cell culture after the expressing or culturing step.

The term "vector" refers to a means for expressing a target gene in a host cell, as exemplified by plasmid vectors, cosmid vectors, and viral vectors such as bacteriophage vectors, adenovirus vectors, retrovirus vectors, and adeno-associated virus vectors. Recombinant vectors may be constructed from plasmids frequently used in the art (e.g., pSC101, pGV1106, pACYC177, ColE1, pKT230, pME290, pBR322, pUC8/9, pUC6, pBD9, pHC79, pIJ61, pLAFR1, pHV14, pGEX series, pET series, and pUC19), phages (e.g., λgt4λB, λ-Charon, λΔz1, and M13), or by engineering viruses (e.g., SV40, etc.).

Within a recombinant vector, a polynucleotide may be operably linked to a promoter. The term "operably linked" is intended to refer to a functional link between a nucleotide sequence of interest and an expression control sequence (e.g., a promoter sequence). When "operably linked," the control element may control the transcription and/or translation of the nucleotide sequence of interest.

Recombinant vectors can typically be constructed as cloning vectors or expression vectors. For recombinant expression vectors, vectors generally available in the relevant technical field for expressing foreign proteins in plant, animal, or microbial cells can be used. Various methods well known in the art can be used to construct recombinant vectors.

For use in hosts such as prokaryotic or eukaryotic cells, recombinant vectors can be constructed depending on the host. For example, if a vector is constructed as an expression vector for use in a prokaryotic host, the vector typically contains a strong promoter for transcription (e.g., pLκλ promoter, CMV promoter, trp promoter, lac promoter, tac promoter, T7 promoter, etc.), a ribosome binding site for translation initiation, and a transcription/translation termination sequence. On the other hand, expression vectors for use in eukaryotic hosts contain an origin of replication operable in eukaryotic cells, such as, but not limited to, the f1 origin of replication, SV40 origin of replication, pMB1 origin of replication, adenovirus origin of replication, AAV origin of replication, and BBV origin of replication. In addition, expression vectors typically include a promoter derived from the genome of a mammalian cell (e.g., a metallothionein promoter) or a promoter derived from a mammalian virus (e.g., an adenovirus late promoter, a vaccinia virus 7.5K promoter, an SV40 promoter, a cytomegalovirus promoter, and an HSV tk promoter), and a polyadenylation sequence as a transcription termination sequence.

Recombinant cells can be prepared by introducing a recombinant vector into a suitable host cell. Any host cell known in the art can be used in the present disclosure, as long as it allows for the sequential cloning and expression of the recombinant vector in a stable manner. Examples of prokaryotic host cells that can be used for the present disclosure include Bacillus species, such as E. coli, Bacillus subtilis, and Bacillus thuringiensis, as well as Enterobacteriaceae strains, such as Salmonella typhimurium and Serratia marcescens, and various Pseudomonas species. Eukaryotic host cells that can be used for transformation can be selected from, but are not limited to, Saccharomyce cerevisiae, insect cells, and animal cells such as Sp2/0, CHO (Chinese hamster ovary) K1, CHO DG44, PER.C6, W138, BHK, COS-7, 293, HepG2, Huh7, 3T3, RIN, and MDCK.

The polynucleotide or a recombinant vector carrying the polynucleotide can be introduced (transfected) into a host cell using methods well known in the relevant art. For example, if the host cell is a prokaryotic cell, transfection can be performed using the CaCl2 method or electroporation. For eukaryotic host cells, gene transfer can be achieved using methods including, but not limited to, microinjection, calcium phosphate precipitation, electroporation, liposome-mediated transfection, or particle bombardment.

To select transformed host cells, the phenotype associated with the selectable marker can be used according to methods well known in the art. For example, if the selectable marker is a gene that confers resistance to a particular antibiotic, the host cells can be grown in the presence of the antibiotic in the medium to select for the desired transformants.

Another embodiment provides a method for producing a bispecific antibody, the method comprising expressing a polynucleotide or recombinant vector in a host cell. In one embodiment, the production method can include culturing recombinant cells harboring the polynucleotide or recombinant vector therein, and optionally isolating and/or purifying the antibody from the culture medium.

Beneficial Effects The present disclosure relates to bispecific antibodies, each of which comprises an antibody specific for a tumor-associated antigen (TAA; HER2) and an antibody specific for 4-1BB, and uses thereof. These bispecific antibodies activate 4-1BB signaling and potently boost immune cells only in the presence of HER2-expressing cells. Due to the specific HER2-mediated immune response, the use of bispecific antibodies is expected to significantly reduce liver toxicity compared to 4-1BB monoclonal antibodies.

1 is a graph showing the antigen (human 4-1BB) binding activity of anti-4-1BB antibodies measured by ELISA. 1 is a graph showing the cell binding activity of anti-4-1BB antibodies measured by ELISA. 1 is a graph showing the antigen (human HER2) binding activity of anti-HER2/anti-4-1BB bispecific antibodies as measured by ELISA. 1 is a graph showing the antigen (human HER2) binding activity of anti-HER2/anti-4-1BB bispecific antibodies as measured by ELISA. 1 is a graph showing the antigen (human 4-1BB) binding activity of anti-HER2/anti-4-1BB bispecific antibodies measured by ELISA. 1 is a graph showing the antigen (human 4-1BB) binding activity of anti-HER2/anti-4-1BB bispecific antibodies measured by ELISA. 1 is a graph showing the level of 4-1BB signal activation in the NCI-N87 cell line (highly HER2-expressing cells) by an anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing the level of 4-1BB signal activation in the MDA-MB231 cell line (HER2-negative cells) by an anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing the level of 4-1BB signal activation in the HER2-expressing NCI-N87 cell line by anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing the level of 4-1BB signal activation in a HER2-expressing Calu-3 cell line by an anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing the level of 4-1BB signal activation in a HER2-expressing HCC1954 cell line by an anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing the level of 4-1BB signal activation in the HER2-expressing JIMT1 cell line by an anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing the level of 4-1BB signal activation in the HER2-expressing ZR-75-1 cell line by anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing the level of 4-1BB signal activation in the non-HER2-expressing A431 cell line by an anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing the level of 4-1BB signal activation in a non-HER2-expressing MCF-7 cell line by an anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing the level of 4-1BB signal activation in the HER2 non-expressing MDA-MB231 cell line by an anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing the level of 4-1BB signal activation in the HER2 non-expressing BxPC-3 cell line by an anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing the level of 4-1BB signal activation in a HER2-expressing Calu-3 cell line by an anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing the level of 4-1BB signal activation in a HER2-expressing HCC1954 cell line by an anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing the correlation of HER2 sABC with 4-1BB-induced NF-kB signaling by anti-HER2/anti-4-1BB bispecific antibodies in various cell lines. 1 is a graph showing IFN-gamma levels released from HER2-expressing HCC1954 cells treated with anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing IFN-gamma levels released from HER2-expressing HCC1954 cells treated with anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing the % survival of HER2-expressing HCC1954 cells treated with anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing the % survival of HER2-expressing HCC1954 cells treated with anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing in vivo anti-tumor activity of anti-HER2/anti-4-1BB bispecific antibody in hPBMC-engrafted mice bearing HCC1954. 1 is a graph showing lymphocyte marker-positive cell counts in HCC1954-bearing hPBMC-engrafted mice treated with anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing in vivo anti-tumor activity of anti-HER2/anti-4-1BB bispecific antibodies in 4-1BB knock-in mice bearing human HER2/MC38 tumors. FIG. 1 is a graph showing in vivo anti-tumor activity by anti-HER2/anti-4-1BB bispecific antibody in mice cured with anti-HER2/anti-4-1BB bispecific antibody and re-challenged with human HER2/MC38 and B16 F10 tumor cells. 1 is a graph showing the antibody-dependent cell-mediated cytotoxicity (ADCC) effect of anti-HER2/anti-4-1BB bispecific antibodies. 1 is a graph showing the results of an FcγRIIb-dependent 4-1BB bioassay for an anti-HER2/anti-4-1BB bispecific antibody. 1 is a graph showing the results of an FcγRIIb-independent 4-1BB bioassay for an anti-HER2/anti-4-1BB bispecific antibody.

MODES OF THE INVENTION Hereinafter, the present invention will be described in detail by way of examples.

The following examples are intended only to illustrate the present invention and are not to be construed as limiting the present invention.

Example 1
1. Anti-4-1BB Antibody 1.1. Preparation of Fully Human Monoclonal Antibody Against 4-1BB Fully human monoclonal anti-4-1BB antibodies in the form of full-length IgG were screened by phage library immunotube panning against 4-1BB. A total of four rounds of panning were performed using immunotubes coated with 4-1BB (NCBI accession number: NP_001552.2) to pan the phage library against the target molecule (obtained from KBio Health and CUREBIO).

Bacterial colonies from the panning output from three rounds were grown in 96-deep-well plates in SB-carbenicillin (Biomatik product number: A2311-5g) until turbid, at which point ¹⁰ pfu of VCSM13 helper phage (K-Bio Health) was added to each well. One hour post-infection, at 37°C with gentle shaking (80 rpm), 70 μg/mL kanamycin was added, and the cells were incubated overnight at 30°C with shaking at 200 rpm.

The next day, the plates were centrifuged, and the phage-containing supernatant was added to a 4-1BB antigen-coated ELISA plate that had been blocked with 3% (v/v) BSA (bovine serum albumin) in PBST (phosphate-buffered saline with Tween 20). After incubation for 1 hour at room temperature, the plate was washed three times with PBST, and anti-M13 antibody (Sino Biological product number: 11973-MM05) was added. The plate was incubated for 1 hour, washed three times with PBST, and binding activity was measured using tetramethylbenzidine (TMB).

4-1BB-specific binders were amplified for sequencing of the plasmid DNA. The light chain variable region sequences and heavy chain variable region sequences (VL and VH sequences) were analyzed to identify unique sequences and determine sequence diversity (underlined: CDR1, CDR2, and CDR3 order), as shown in Tables 6-13. In the following examples, an anti-4-1BB antibody designated as BMUR (Urelumab from BMS, U.S. Patent No. 7,288,638) is used to compare agonist activity.

1.2. Preparation of scFv Antibody Against 4-1BB Antibodies with the structure (N')-VL-linker-VH-(C') were prepared using the variable regions of fully human monoclonal antibodies against 4-1BB shown in Tables 6 to 13 in Example 1.1, in which the amino acid residue "G" at position 44 of the heavy chain variable region was substituted with "C" and the amino acid residue "G" at position 103 of the light chain variable region was substituted with "C." Such a "G" to "C" amino acid substitution within the scFv may contribute to increased stability of bispecific antibodies that include the scFv as one target-specific moiety. The amino acid sequences of the prepared anti-4-1BB scFvs are exemplified in Tables 14 to 19 below, but those skilled in the art can apply changes or modifications to the amino acid sequences in the following embodiments to meet specific purposes, including the application of various types of peptide linkers, such as (GGGGS)2, (GGGGS)3, (GGGGS)4, or (GS)9.

1.3. Antigen-binding ability of anti-4-1BB antibodies (full-length IgG form) to human 4-1BB (1) Antigen-binding activity measured by ELISA To assess antigen-binding activity, the antibody candidates prepared in Example 1.1 were subjected to an ELISA test. Briefly, microtiter plates were coated with 0.1 μg/ml human 4-1BB-Fc protein (Sino Biological) in PBS, 100 μl per well, overnight at 4°C, and then blocked with 5% (v/v) BSA, 100 μl per well. Five-fold dilutions of humanized antibodies (1A10, 1A12, and AB41), starting from 10 μg/ml, were added to each well and incubated at room temperature (RT) for 1 to 2 hours. Plates were washed with PBS/Tween and then incubated with goat anti-human IgG antibody conjugated to horseradish peroxidase (HRP) (Thermo) for 1 hour at RT. After washing, plates were developed with TMB substrate and analyzed by spectrophotometry at OD 450-650 nm.

The results are shown in Figure 1a. As shown in Figure 1a, all of the tested anti-4-1BB antibodies exhibited 4-1BB binding ability.

(2) Cell Binding Activity Measured by FACS To assess cell binding activity, antibody candidates were analyzed for their binding to mammalian-expressed 4-1BB by fluorescence-activated cell sorting (FACS). Briefly, GloResponse™ NFκB-luc2/4-1BB Jurkat cell line (Promega; 3× ¹⁰ cells), which express 4-1BB on their surface, was incubated with antibodies (1A10 and 1A12; each at 10 μg/mL). After washing with FACS buffer (1% (v/v) BSA in PBS), FITC-anti-human IgG antibody (Sigma, F9512, concentration: 2.0 mg/mL) was added to each well and incubated at 4°C for 1 hour. The mean fluorescence intensity (MFI) of FITC was assessed by FACSCalibur (BD Biosciences).

The results are shown in Figure 1b. As shown in Figure 1b, all of the tested anti-4-1BB antibodies exhibited the ability to bind to 4-1BB expressed on the cell surface and could efficiently bind to 4-1BB expressed on mammalian cells.

Example 2
Preparation of anti-HER2 antibodies For the anti-HER2/anti-4-1BB bispecific antibody, trastuzumab (Genentech; hereinafter referred to as "HER2 (WT)", DrugBank accession number: DB00072; human IgG1 kappa monoclonal antibody) or an antigen-binding fragment thereof, such as scFv, was used as the HER2-targeting moiety.

The sequence of HER2 (WT) is summarized in Table 20 below.

The constant region of the anti-HER2 antibody contained within the bispecific antibody can be modified by introducing more than one mutation or change into human IgG1, one exemplary embodiment, HER2(NA or N297A), is presented in Table 20 below.

Example 3
Preparation of anti-HER2/anti-4-1BB bispecific antibodies Various anti-HER2/anti-4-1BB bispecific antibody candidates were prepared in the full-length IgG (anti-HER2 antibody)-scFv (anti-4-1BB antibody) format or the full-length IgG (anti-4-1BB antibody)-scFv (anti-HER2 antibody) format. In this example, the anti-HER2 IgG and 4-1BB scFv clones prepared in Example 2 and Example 1.2, respectively, were selected as exemplary clones to prepare anti-HER2/anti-4-1BB bispecific antibodies in the IgG-scFv fusion form (in which the scFv antibody fragment of one antigen was fused to the C-terminus of the IgG fragment of another antigen). When HER2 was placed in the full IgG moiety, IgG1 with a mutant backbone that reduced ADCC (e.g., N297A mutation; Cancer Cell, Vol. 19, No. 1, pp. 101-113) was used, and when 4-1BB was placed in the full IgG moiety, IgG4 was used.

DNA segment 1, containing the nucleotide sequence encoding the heavy chain of the IgG antibody of the anti-HER2/anti-4-1BB bispecific antibody, was inserted into pcDNA 3.4 (Invitrogen, A14697; Plasmid 1), and DNA segment 2, containing the nucleotide sequence encoding the light chain of the IgG antibody of the anti-HER2/anti-4-1BB bispecific antibody, was inserted into pcDNA 3.4 (Invitrogen, A14697; Plasmid 2). To construct a vector for expressing the bispecific antibody, DNA segment 3, encoding the scFv, was fused to the portion of DNA segment 1 inserted into Plasmid 1 corresponding to the C-terminus of the Fc region of the IgG antibody using either DNA segment 4, encoding a 15-amino acid linker peptide consisting of (GGGGS)3, or DNA segment 5, encoding an 18-amino acid linker peptide consisting of (GS)9. Furthermore, as described in Example 1.2, to stabilize the scFv, a further modification was applied in which VL103-VH44 (VL103: VL with a G→C mutation at position 103; VH44: VH with a G→C mutation at position 44) was fused to the C-terminus of the light chain and the C-terminus of the heavy chain, respectively, to create a disulfide bridge.

Among the bispecific antibodies prepared, the sequences of the heavy chain, light chain, scFv, and DNA segments used in the preparation of some exemplary bispecific antibodies are exemplified in Tables 21 to 29. In the antibodies presented below, one or more point mutations can be applied within the amino acid sequence for purposes such as improving stability and titer, reducing immunogenicity, etc.

Example 4
4.1 Testing the Binding Affinity of Bispecific Antibodies (BsAbs) Binding to Human HER2 The binding affinity of bispecific antibodies to HER2 was determined by ELISA, as described in Example 1.3(1). Briefly, 96-well microtiter plates (Nunc-Immuno Plates, NUNC) were coated with 1 μg/ml human HER2-His protein (Sino Biological, 10004-H08H) in PBS at 100 μl per well overnight at 4°C, and then blocked with blocking buffer (1% (v/v) BSA (bovine serum albumin (Gibco, 30063572) in PBS at 200 μl per well) at 37°C for 2 hours. Serial dilutions (starting from 0.1 μM) of the anti-HER2/anti-4-1BB bispecific antibody prepared in Example 3 and a control anti-HER2 antibody (HER2(NA)) were added to each well and incubated at 37°C for 1 hour. The plate was washed with PBS/0.05% Tween 20 and incubated with an HRP-conjugated Fab antibody (Pierce, 31414) at 37°C for 1 hour. After washing, the plate was developed with TMB (tetramethylbenzidine, Sigma, T0440) substrate and analyzed by spectrophotometer at OD of 450-650 nm.

The results are shown in Figures 2a and 2b. As shown in Figures 2a and 2b, all of the tested anti-HER2/anti-4-1BB bispecific antibodies were able to bind to human HER2 protein with high affinity, similar to that of the control anti-HER2 antibody (NA).

The binding affinity of the bispecific antibody to 4-1BB was determined by ELISA as described in Example 1.3(1). Briefly, 96-well microtiter plates (Nunc-Immuno Plates, NUNC) were coated with 1 μg/ml human 4-1BB-His protein (Sino Biological, 10041-H08H) in PBS at 100 μl per well overnight at 4°C, and then blocked with blocking buffer (1% (v/v) BSA (bovine serum albumin (Gibco, 30063572) in PBS at 200 μl per well) at 37°C for 2 hours. Serial dilutions (starting from 0.1 μM) of the anti-HER2/anti-4-1BB bispecific antibody prepared in Example 3 and a control anti-HER2 antibody (HER2(NA)) were added to each well and incubated at 37°C for 1 hour. The plate was washed with PBS/0.05% Tween 20 and incubated with an HRP-conjugated Fab antibody (Pierce, 31414) for 1 hour at 37°C. After washing, the plate was developed with TMB substrate and analyzed by spectrophotometer at OD of 450-650 nm.

The results are shown in Figures 3a and 3b. As shown in Figures 3a and 3b, all of the tested anti-HER2/anti-4-1BB bispecific antibodies were able to bind to human 4-1BB protein with high affinity, whereas the anti-HER2 antibody did not bind to human 4-1BB protein.

The results of Figures 2a, 2b, 3a, and 3b were quantified and are summarized in Table 30 below.

As shown in Table 30, all of the tested anti-HER2/anti-4-1BB bispecific antibodies were able to bind with high affinity to both human HER2 protein and human 4-1BB protein.

4.3. Binding to diverse cell surface-expressed human HER2 The binding affinity of the bispecific antibody to diverse cells expressing HER2 on their surface was determined by FACS analysis, see Example 1.3(2).

Various tumor cell lines listed in Table 31 were used. After dissociating each cell line and washing it with PBS, the cell number was counted and set at 2 x ¹⁰ cells per 100 µl of FACS buffer. Then, the cells were treated with an anti-HER2 antibody or an anti-HER2/anti-4-1BB bispecific antibody at 10 µg/mL and reacted at 4°C for 1 hour. After the reaction, the cells were washed in FACS buffer and then suspended in 2 µl of a FITC-labeled constant region (Fc)-specific antibody (goat anti-human IgG FITC-conjugated Fc-specific antibody, Sigma, F9512, concentration: 2.0 mg/ml) to give 2 x ¹⁰ cells per 100 µl of FACS buffer and reacted at 4°C for 1 hour. After the reaction, the cells were washed in FACS buffer and analyzed using a FACSCalibur device. The negative control group was treated with only FITC-labeled constant region (Fc)-specific antibody. To compare the expression levels of HER2 among cancer cell lines, the value for the peak shift results in the test group was divided by the value for the peak shift results in the negative control group (Mean Fluorescence Intensity Ratio = MFI ratio: MFI for test antibody/MFI for second antibody).

The results obtained are shown in Table 31 below.

As shown in Table 31, all tested anti-HER2/anti-4-1BB bispecific antibodies were capable of binding to cell surface-expressed human HER2 protein.

Example 5
Binding affinity of BsAb to 4-1BB (SPR)
In SPR experiments, flow cell 1 on a Biocore® Series S Sensor Chip CM5 (GE Healthcare, BR100530), on which an anti-human Fab antibody (GE Healthcare, 28958325) was immobilized by amine coupling, was held as a reference, while the anti-HER2/anti-4-1BB bispecific antibody was captured individually on flow cells 2, 3, and 4. Recombinant human 4-1BB protein (ACROBiosystems, 41B-H5227) was flowed across the chip at concentrations of 400, 200, 100, 50, 25, 12.5, 6.25, 3.13, 1.56, and 0.78 nM at 30 μl/min for 300 seconds, followed by a 400-second dissociation phase. Regeneration was performed with 10 mM glycine-HCl (pH 2.0) (GE Healthcare, BR100355).

The results obtained are shown in Table 32 below.

As shown in Table 32, the tested anti-HER2/anti-4-1BB bispecific antibodies exhibit high 4-1BB binding affinity.

Example 6
6.1 Activation of 4-1BB Signaling BsAb vs. Monospecific Antibodies In this example, to measure activation of 4-1BB signaling, GloResponse™ NFκB-luc2/4-1BB Jurkat cell line (Promega), which was genetically modified to stably express human 4-1BB and luciferase downstream of the response element, was used as effector cells, and cancer cells expressing or not expressing HER2 were used as target cells. Briefly, target cells, NCI-N87 (expressing HER2; 2.5 × 10 ⁴ cells) or MDA-MB-231 (not expressing HER2; 2.5 × 10 ⁴ cells), were seeded into 96-well assay plates and cultured overnight. On the day of the assay, the test anti-HER2/anti-4-1BB bispecific antibody (Example 3) and effector Jurkat cells (2.5 x ¹⁰ cells) were added to the plate. After 6 hours of incubation, Bio-Glo™ reagent (Promega) was added and luminescence was measured using a microplate reader.

The results are shown in Figures 4a (NCI-N87 cell line) and 4b (MDA-MB-231 cell line) below. In Figures 4a and 4b, BMUR (Urelumab from BMS, U.S. Patent No. 7,288,638) indicates the anti-4-1BB antibody used to compare agonist activity. As shown in Figures 4a and 4b, the anti-HER2/anti-4-1BB bispecific antibody potently activates 4-1BB signaling only when co-cultured with HER2-highly expressing cells. The Fc-bridged anti-4-1BB monoclonal antibody showed minimal activity.

6.2. Activation of 4-1BB in various HER2-expressing cells (I)
In this example, to measure activation of 4-1BB signaling, GloResponse™ NFκB-luc2/4-1BB Jurkat cell line (Promega), genetically engineered to stably express human 4-1BB and luciferase downstream of the response element, was used as effector cells, and cancer cells expressing or not expressing HER2 were used as target cells. Briefly, HER2-expressing (NCI-N87, Calu-3, HCC1954, JIMT1, ZR-75-1) or HER2-non-expressing (MDA-MB231, MCF-7, A431, BxPC-3) cancer cells (2.5 x ¹⁰ cells per well) were seeded into 96-well assay plates and cultured overnight. On the day of the assay, test anti-HER2/anti-4-1BB bispecific antibodies (Example 3; 15 nM, 4-fold dilution, or 20 nM, 5-fold dilution, or 100 nM, 5-fold dilution) and effector Jurkat cells (2.5 x ¹⁰ cells per well) were added to the plates. After 6 hours of incubation, Bio-Glo™ reagent was added and luminescence was measured using a microplate reader.

The results are shown in Figures 5a to 5i. As shown in Figures 5a to 5i, the anti-HER2/anti-4-1BB bispecific antibody strongly activated 4-1BB signaling only when co-cultured with HER2-expressing cells.

6.3. Activation of 4-1BB in various HER2-expressing cells (II)
In this example, to measure activation of 4-1BB signaling, the GloResponse™ NFκB-luc2/4-1BB Jurkat cell line (Promega), genetically engineered to stably express human 4-1BB and luciferase downstream of the response element, was used as effector cells. Briefly, HER2-expressing target cells (Calu-3 or HCC1954; 2.5 x ¹⁰ cells per well) were seeded into a 96-well assay plate and cultured overnight. On the day of the assay, the test anti-HER2/anti-4-1BB bispecific antibody (Example 3; 20 nM, 5-fold dilution, or 133 nM, 6-fold dilution) and effector Jurkat cells (2.5 x ¹⁰ cells per well) were added to the plate. After 6 hours of incubation, Bio-Glo™ reagent was added and luminescence was measured using a microplate reader.

The results are shown in Figures 6a and 6b. As shown in Figures 6a and 6b, all tested anti-HER2/anti-4-1BB bispecific antibodies induced strong activation of 4-1BB signaling only when co-cultured with highly HER2-expressing cells.

6.4. HER2 Quantification The cell surface expression level of HER2 was quantified on various cancer cell lines using the QIFIKIT quantification kit (Dako) according to the manufacturer's recommendations. Briefly, cells were stained with a saturating concentration of unlabeled anti-HER2 mouse monoclonal antibody (R&D systems) or purified mouse IgG2b isotype control (R&D systems). After washing, the stained cells and calibration beads provided by the kit were simultaneously labeled with the same FITC-conjugated goat anti-mouse IgG secondary antibody provided by the kit. The labeled cells and calibration beads were analyzed on a flow cytometer. Linear regression was performed using the MFI values from the calibration beads. ABC (antibody-binding capacity) was extrapolated from this regression line, and sABC (specific ABC) was determined by subtracting the ABC of the isotype control antibody from the ABC of the anti-HER2 antibody.

The results obtained are shown in Table 33.

The sABC of nine cancer cell lines was determined as shown in Table 33.

6.5 Correlation of HER2 sABC with 4-1BB-Induced NF-kB Signaling The HER2 levels measured in Example 6.4 were normalized to the HER2 levels expressed by HCC1954. The level of 4-1BB activation by the bispecific antibody was determined as the highest level of fold change compared to the control in the 4-1BB NF-kB luciferase reporter assay of Example 6.2. The intersection area indicates the confidence interval for the linear fit.

The results are shown in Figure 7. As shown in Figure 7, 4-1BB activation by the anti-HER2/anti-4-1BB bispecific antibody showed a strong correlation with cell surface expression of HER2.

Example 7
7.1 Effect on T Cell Immune Responses 7.1. Effect on Cytokine Release To examine the ability of bispecific antibodies to stimulate responses in human peripheral blood mononuclear cells (PBMCs), the supernatant concentration of IFN-gamma was measured. Human PBMCs were co-cultured with HER2-expressing HCC1954 cancer cells in the presence of a human anti-CD3 antibody (BioLegend, 5 μg/mL) and the test bispecific antibody (Example 3; 3 μg/mL, 4-fold dilution). After 72 hours of incubation in a humidified chamber at 37°C with 5% _CO2 , the supernatant concentration of IFN-gamma was measured using a human IFN-gamma Quantikine kit (R&D systems, SIF50).

The results are shown in Figures 8a to 8d. As shown in Figures 8a to 8d, all of the tested bispecific antibodies induced greater cytokine release than the combination of each monoclonal antibody in the presence of highly HER2-expressing cells.

7.2 Effect on Target Cell Proliferation A target cell lysis assay was used to examine the ability of the bispecific antibody to stimulate a response in human PBMCs. Human PBMCs were co-cultured with HER2-expressing HCC1954 cancer cells in the presence of a human anti-CD3 antibody (BioLegend, 5 μg/mL) and the test bispecific antibody (Example 3; 3 μg/mL, 4-fold dilution). After 72 hours of incubation in a humidified chamber at 37°C with 5% _CO2 , the viability of HCC1954 cells was measured using a Cell Counting Kit-8 (Dojindo, CK04-20).

The results are shown in Figures 9a to 9d. As shown in Figures 9a to 9d, all of the tested bispecific antibodies exhibited superior cancer cell killing activity in the presence of highly HER2-expressing cells compared to the combination of each monospecific antibody.

Example 8
8.1 In Vivo Antitumor Effect in HCC1954-Bearing hPBMC-Engrafted Mice Antitumor Activity To investigate the in vivo antitumor effect of the anti-HER2/anti-4-1BB bispecific antibody, PBMC-humanized NSG mice were used. Seven-week-old NSG mice (Jackson Laboratory) were intravenously injected with 1 x ¹⁰ human PBMCs, and HCC1954 cancer cells (1 x 10 per mouse in a ¹ :1 solution of Matrigel in PBS) were inoculated into the right flank of the mice. Two days after tumor implantation, the HCC1954-bearing humanized mice were assigned to each test group (n = 12 per group). Mice were intravenously administered human IgG1 control antibody, anti-4-1BB antibody, or anti-HER2/anti-4-1BB bispecific antibody at doses of 10 mg/kg or 7.5 mg/kg twice weekly for 4 weeks. Antibody was injected twice weekly, and tumor size was measured with digital calipers.

The results are shown in Figure 10. As shown in Figure 10, all of the tested bispecific antibodies exhibited superior anti-tumor activity to the reference anti-4-1BB antibody (urelumab, BMS) and the control antibody.

8.2 Analysis of Tumor-Infiltrating Lymphocytes (TILs) To assess TILs, formalin-fixed, paraffin-embedded tumor tissue sections from HCC1954-bearing hPBMC-engrafted mice were immunostained with anti-hCD45 antibody (human leukocyte marker, Cell Signaling Technology), anti-hCD4 antibody (human helper T lymphocyte marker, Cell Signaling Technology), anti-hCD8 antibody (human cytotoxic T lymphocyte marker, Cell Signaling Technology), and anti-hCD16 antibody (human natural killer cell marker, Cell Signaling Technology). Immunohistochemistry was performed using an avidin-biotin detection kit (Vector Laboratories) to measure the number of cells positive for each marker. Briefly, formalin-fixed, paraffin-embedded tumor tissue sections were deparaffinized and rehydrated. Antigen retrieval from the rehydrated tissue sections was performed by placing the sections in EDTA buffer (pH 9.0). After washing with phosphate-buffered saline (PBS) and incubation with blocking solution for 30 minutes, the sections were incubated with primary antibodies overnight at 4°C. The Vectastain Elite ABC kit (Vector Lab) and the protocol provided by the manufacturer were used for immunostaining. The sections were then counterstained with hematoxylin, dehydrated using medical-grade alcohol and xylene, and mounted with Permount.

The results are shown in Figure 11. As shown in Figure 11, the Her2x41-BB bispecific antibody effectively enhanced the infiltration of immune cells, including CD45 ⁺ cells, CD4 ⁺ T cells, CD8 ⁺ T cells, and NK cells, into tumor tissues compared to BMUR (urelumab).

Example 9
9. In vivo anti-tumor effect in 4-1BB knock-in mice 9.1 Anti-tumor activity The in vivo anti-tumor effect of the anti-HER2/anti-4-1BB bispecific antibody was assessed in 4-1BB knock-in mice (Biocytogen) bearing human HER2/MC38 tumors (Biocytogen). Tumor-bearing humanized mice were randomized into each test group (n=5 per group) based on tumor volume (approximately 80 mm ³ ) 4 days after tumor implantation. The human IgG1 antibody trastuzumab (anti-HER2 antibody) and the anti-HER2/anti-4-1BB bispecific antibody (HER2(WT)x1A10 M12, HER2(NA)x1A10 M12) were intraperitoneally administered to mice at a dose of 10 mg/kg or 7.5 mg/kg, respectively, twice weekly for 4 weeks. Tumor size was measured with a digital caliper.

The results are shown in Figure 12. As shown in Figure 12, the anti-HER2/anti-4-1BB bispecific antibody exhibited superior anti-tumor effects compared to trastuzumab in human HER2/MC38 tumors. Notably, tumors in all mice treated with HER2(WT) x 1A10 M12 were cured.

9.2. Assessment of the Effect of Tumor-Specific Memory T Cells Mice cured with HER2(WT) x 1A10 M12 were rechallenged with human HER2/MC38 tumor cells (Biocytogen) and B16F10 tumor cells (ATCC) in both flanks 63 days after tumor injection. Mice were drug-free during the rechallenge study. Tumor size was measured with digital calipers.

The results are shown in Figure 13. As shown in Figure 13, no human HER2/MC38 tumors were observed to develop, whereas B16 F10 tumors grew even in mice cured by HER2(WT) x 1A10 M12 treatment.

Example 10
Antibody-dependent cell-mediated cytotoxicity (ADCC) activity (NA scaffold vs. WT)
10.1. NK cell-mediated ADCC
In this example, human peripheral blood-derived CD56 ⁺ NK cells were used as effector cells, and CellTrace Violet (Thermo Fisher Scientific)-labeled HCC1954 cells expressing HER2 were used as target cells. The cells were co-cultured at 37°C with 50 nM of anti-HER2/anti-4-1BB bispecific antibody (Example 3) at an effector:target ratio of 5:1. After 4 hours, the cells were stained with Fixable Viability dye (eBioscience™), and the ratio of target dead cells was then analyzed by flow cytometry.

The results are shown in Figure 14 below. As shown in Figure 14, the IgG1 type (WT) anti-HER2/anti-4-1BB bispecific antibody exhibited a significant ADCC effect mediated by NK cells.

10.2. 4-1BB Signal Activation Depends on FcγRIIb Engagement In this example, FcγRIIb-expressing CHO-K1 cells (Promega) were seeded into a 96-well assay plate and cultured overnight. On the day of the assay, Jurkat/4-1BB cells (Promega) were seeded into the 96-well plate. The cells were incubated with titrated amounts of anti-HER2/anti-4-1BB bispecific antibody in the presence (FcγRIIb-dependent) or absence (FcγRIIb-independent) of FcγRIIb-expressing CHO-K1 cells (Promega). Six hours after induction, Bio-Glo™ Luciferase Assay Reagent was added and luminescence was determined using a SpectraMax L luminometer (Molecular Devices). Four-parameter logistic curve analysis was performed with GraphPadPrism® software.

The results obtained are shown below in Tables 34 (FcγRIIb-dependent 4-1BB bioassay) and 35 (FcγRIIb-independent 4-1BB bioassay) and in Figures 15a (FcγRIIb-dependent 4-1BB bioassay) and 15b (FcγRIIb-independent 4-1BB bioassay).

As shown in Tables 34 and 35 and Figures 15a and 15b, the urelumab-treated group showed a 13.5-fold difference in maximum RLU and a 2.2-fold difference in _EC50 in the presence of FcγRIIb CHO-K1 cells. The four anti-HER2/anti-4-1BB bispecific antibodies showed significantly lower RLU compared to urelumab, regardless of the presence or absence of FcγRIIb CHO-K1 cells. These data indicated that all tested anti-HER2/anti-4-1BB bispecific antibodies offer potential benefits compared to urelumab, which caused severe toxicity in clinical studies (NCT00309023, NCT00612664, NCT014712210).

All references cited herein, including publications, patent applications, and patents, are incorporated by reference to the same extent as if each reference was individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

Unless otherwise indicated herein or the context clearly dictates to the contrary, in the context of describing the invention (particularly in the context of the claims below), the use of the terms "a" and "an" and "the" referents, as well as "at least one" and "one or more" referents, and similar referents, shall be understood to cover both the singular and plural referents. Unless otherwise indicated herein or the context clearly dictates to the contrary, the use of the term "at least one" (or "one or more") following one or more items in a list (e.g., "at least one of A and B") shall be understood to mean one item (A or B) selected from the listed items, or any combination of two or more of the listed items (A and B). The terms "comprising," "having," "including," and "containing" are to be understood as open-ended terms (i.e., meaning "including, but not limited to") unless otherwise noted. Unless otherwise indicated herein, the recitation of ranges of values herein is intended only as a shorthand method of referring individually to each separate value falling within the range, and each separate value is incorporated into the specification as if it were individually recited herein. Unless otherwise indicated herein or unless the context clearly dictates otherwise to the contrary, all methods described herein can be performed in any suitable order. The use of any and all examples or exemplary language (e.g., "etc.") presented herein is intended only to better illustrate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language herein should be construed as indicating any non-claimed element as essential to the practice of the invention.

Preferred embodiments of the present invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of these preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect that skilled artisans will employ such variations where appropriate, and the inventors intend that the invention may be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Furthermore, any combination of the above-described elements in all possible variations thereof is encompassed by the present invention unless otherwise indicated herein or the context clearly dictates otherwise to the contrary.

Claims (24)

(a) an anti-4-1BB antibody or an antigen-binding fragment thereof, and (b) an anti-HER2 antibody or an antigen-binding fragment thereof, wherein the anti-4-1BB antibody or antigen-binding fragment thereof is
(1) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 1, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 4, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 7, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 12, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 14, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 16;
(2) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 1, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 4, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 8, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 12, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 14, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 16;
(3) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 1, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 4, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 9, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 12, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 14, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 16; or
(4) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 2, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 5, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 10, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 12, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 14, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 16;
1. An anti-4-1BB/anti-HER2 bispecific antibody comprising : The anti-4-1BB antibody or antigen-binding fragment thereof is
(1) a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 18 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 30, or a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 24 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 33;
(2) a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 19 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 30 or 31, or a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 25 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 33 or 34;
(3) a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 20 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 30 or 31; or
(4) A heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 21 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 30, a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 22 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 31, or a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 27 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 33, or a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 28 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 34
2. The anti-4-1BB/anti-HER2 bispecific antibody of claim 1, comprising : The anti-4-1BB antibody or antigen-binding fragment thereof is
(1) a heavy chain comprising the amino acid sequence of SEQ ID NO: 56 and a light chain comprising the amino acid sequence of SEQ ID NO: 62;
(2) a heavy chain comprising the amino acid sequence of SEQ ID NO: 57 and a light chain comprising the amino acid sequence of SEQ ID NO: 62 or 63;
(3) a heavy chain comprising the amino acid sequence of SEQ ID NO: 58 and a light chain comprising the amino acid sequence of SEQ ID NO: 62 or 63; or
(4) A heavy chain comprising the amino acid sequence of SEQ ID NO: 59 and a light chain comprising the amino acid sequence of SEQ ID NO: 62, or a heavy chain comprising the amino acid sequence of SEQ ID NO: 60 and a light chain comprising the amino acid sequence of SEQ ID NO: 63
The anti-4-1BB/anti-HER2 bispecific antibody of claim 1 or 2, comprising : The anti-4-1BB/anti-HER2 bispecific antibody according to claim 1 or 2, wherein the anti-4-1BB antibody or antigen-binding fragment thereof is an anti-4-1BB scFv of the anti-4-1BB antibody. The anti-4-1BB/anti-HER2 bispecific antibody of claim 4, wherein the anti-4-1BB scFv further comprises a peptide linker between the heavy chain variable region and the light chain variable region. The anti-4-1BB/anti-HER2 bispecific antibody of any one of claims 1 to 5, wherein the anti-HER2 antibody is trastuzumab, pertuzumab, or trastuzumab emtansine (T-DM1). The anti-HER2 antibody or antigen-binding fragment thereof is
H-CDR1 comprising the amino acid sequence of SEQ ID NO: 65;
H-CDR2 comprising the amino acid sequence of SEQ ID NO: 66;
H-CDR3 comprising the amino acid sequence of SEQ ID NO: 67;
L-CDR1 comprising the amino acid sequence of SEQ ID NO: 68;
L-CDR2 comprising the amino acid sequence of SEQ ID NO: 69; and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 70.
The anti-4-1BB/anti-HER2 bispecific antibody of any one of claims 1 to 6, comprising: The anti-HER2 antibody or antigen-binding fragment thereof is
8. The anti-4-1BB/anti-HER2 bispecific antibody of claim 1 , comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 71, and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 72. The anti-HER2 antibody or antigen-binding fragment thereof is
9. The anti-4-1BB/anti-HER2 bispecific antibody of any one of claims 1 to 8, comprising a heavy chain comprising the amino acid sequence of SEQ ID NO: 73 or 74; and a light chain comprising the amino acid sequence of SEQ ID NO: 75. The anti-4-1BB/anti-HER2 bispecific antibody according to any one of claims 1 to 8, wherein the anti-HER2 antibody or antigen-binding fragment thereof is an anti-HER2 scFv of the anti-HER2 antibody. The anti-4-1BB/anti-HER2 bispecific antibody of claim 10, wherein the anti-HER2 scFv further comprises a peptide linker between the heavy chain variable region and the light chain variable region. (a) a full-length form of an anti-HER2 antibody, and an scFv of an anti-4-1BB antibody; or
(b) the full-length form of the anti-4-1BB antibody, and the scFv of the anti-HER2 antibody
The anti-4-1BB/anti-HER2 bispecific antibody of any one of claims 1, 2 and 6 to 8, comprising: 9. The anti-4-1BB/anti-HER2 bispecific antibody of any one of claims 1, 2 and 6 to 8, comprising: a polypeptide comprising the amino acid sequence of SEQ ID NO: 76, 77, 78, 79, 80, 81, 82, 83 or 84; and a polypeptide comprising the amino acid sequence of SEQ ID NO: 75. 9. The anti-4-1BB/anti-HER2 bispecific antibody of any one of claims 1, 2 and 6 to 8, comprising: a polypeptide comprising the amino acid sequence of SEQ ID NO: 83; and a polypeptide comprising the amino acid sequence of SEQ ID NO: 75. A pharmaceutical composition for treating or preventing cancer, comprising the anti-4-1BB/anti-HER2 bispecific antibody of any one of claims 1 to 14 and a pharmaceutically acceptable carrier. The pharmaceutical composition of claim 15, wherein the cancer is characterized by expression of HER2. A pharmaceutical composition for enhancing an immune response, comprising the anti-4-1BB/anti-HER2 bispecific antibody of any one of claims 1 to 14 and a pharmaceutically acceptable carrier. An anti-4-1BB/anti-HER2 bispecific antibody described in any one of claims 1 to 14 for use in the treatment or prevention of cancer. The anti-4-1BB/anti-HER2 bispecific antibody of claim 18, wherein the cancer is characterized by expression of HER2. An anti-4-1BB/anti-HER2 bispecific antibody described in any one of claims 1 to 14 for use in enhancing immune responses. A polynucleotide encoding the anti-4-1BB/anti-HER2 bispecific antibody of any one of claims 1 to 14. A recombinant vector comprising the polynucleotide of claim 21. A recombinant cell comprising the polynucleotide of claim 21. A method for preparing the anti-4-1BB/anti-HER2 bispecific antibody of any one of claims 1 to 14, comprising expressing the polynucleotide of claim 21 in a cell.